Bronchial Tree Casts, Lobe Weights and Anatomical Dead Space Measurements in the Dog's Lung

A method is described for making bronchial tree casts using a polystyrene resin, Bioplastic. The lung is first air dried under pressure and then filled with the resin by gravity while the plastic polymerizes. The pulmonary vessels may also be injected, yielding a double cast. The relative weights of individual lobes of the dog's lung after air drying are presented. A linear relationship is established between the dead space volume of individual lobes and their dry weight. Variations in length of the bronchial systems supplying each lobe may modify the relation between anatomical dead space and weight in that lobes supplied by short bronchial pathways seem to have smaller dead space/weight ratios than those supplied by longer bronchial pathways.